Peripheral Simulation

For NXP (founded by Philips) P89C669 — Serial UART 0 (Enhanced Interface with S0STAT and special BRG)

Simulation support for this peripheral or feature is comprised of:

• Dialog boxes which display and allow you to change peripheral configuration.
• VTREGs (Virtual Target Registers) which support I/O with the peripheral.

These simulation capabilities are described below.

Parallel Port 4 Dialog

This dialog displays the SFR and pins of Port 4.

• P4: This is the P4 SFR. The HEX value and value of each bit is displayed and may be changed from this dialog.
• Pins: These are the states of the pins on the simulated MCU. When used as outputs, these have the same value as the P4 SFR. When used as inputs (P4.x is 1) you may set the level of the input pin to high (1) or low (0).

Serial Channel #0 Dialog

PORTx VTREG
Data Type: unsigned char

The PORTx VTREGs represent the I/O pins of the simulated MCU for Port 0, Port 1, and so on. PORT0 represents Port 0, PORT1 represents Port 1, etc. You may read PORTx to determine the state of the output pins of that port. For example, in the command window, you may type,

PORT0

to obtain value corresponding to the set pins of Port 0. You may also change the input values of port pins by changing the value of the VTREG. For example,

PORT1=0xF0

sets the upper four port pins of Port 1 to a value of 1 and the lower 4 port pins to a value of 0. You may use the bitwise operators AND(&), OR(|) and XOR(^) to change individual bits of the PORTx VTREGs. For example:

PORT1 |=  0x01;  /* Set P1.0 Pin */
PORT3 &= ~0x02;  /* Clr P3.1 Pin */
PORT1 ^=  0x80;  /* Toggle P1.7 Pin */

S0IN VTREG
Data Type: unsigned int

The S0IN VTREG represents the serial input of the simulated microcontroller. Values you assign to S0IN are input to the serial channel. You may assign input using the command window. For example,

S0IN='A'

causes the simulated microcontroller serial input to receive the ASCII character A. If you want to use the S0IN VRTEG to simulate reception of multiple characters, you must be sure to delay for atleast one character time between successive assignments to S0IN. This may be done using a signal function. For example:

signal void send_cat (void) {
swatch(0.01);  /* Wait 1/100 seconds */
S0IN='C';       /* Send a C */
swatch(0.01);
S0IN='A';
swatch(0.01);
S0IN='T';
}

You may use the S0IN VTREG to input more than 8 bits of data. For example,

S0IN=0x0123

inputs a 9-bit value. This is useful if you use 9-bit serial I/O. In addition to the S0IN VRTEG, the serial window allows you to input serial characters by simply typing. Serial characters that are transmitted byt the simulated microcontroller appear in the serial window.

S0OUT VTREG
Data Type: unsigned int

The S0OUT VTREG represents the serial output from the simulated microcontroller. Whenever the simulated serial port transmits a character, the value transmitted is automatically assigned to S0OUT (which is read-only). You may read the value of S0OUT to determine the character transmitted by your simulated program. For example,

S0OUT

outputs the value of the last character transmitted. You may use the S0OUT VTREG in a script to process transmitted data. For example,

signal void s0out_sig (void) {
while (1)
  {
  wwatch(S0OUT);     /* wait for something in S0OUT */
  printf ("Transmitted a %2.2X\n", (unsigned) S0OUT);
  }
}

S0TIME VTREG
Data Type: unsigned char

The S0TIME VTREG allows you to control the timing of the simulated serial port.

• A value of 1 (which is the default) indicates that the serial port timing is identical to the target hardware. Use this value when you want to see the effects of baud rate on the serial port I/O.
• A value of 0 indicates that all serial input and output occur instantaneously. Use this value when you don't care about any baud rate effects or when you want serial output to be fast.

For example:

S0TIME = 0   /* Set Serial Port for FAST timing */
S0TIME = 1   /* Set Serial Port for accurate timing */